Lasiomyrma, a new stenammine ant genus from Southeast Asia (Hymenoptera: Formicidae)

Entomological Science, 2000, 3(3): 523-527

Lasiomyrma, a New Stenammine Ant Genus from Southeast Asia
(Hymenoptera: Formicidae)

Mamoru TERAYAMA 1 and Seiki YAMANE

l 2-12-29-3, Naka-cho, Iwatsuki, 339-0054 Japan

Department of Earth and Environmental Sciences, Faculty of Science, Kagoshima University, Kagoshima, 890-0065

Japan

Abstract. A new stenammine ant genus, Lasiomyrma, is described from Indonesia and Malaysia.
This genus is characterized by the 11 -segmented antennae with a 3-segmented club, the obtusely
angulate anterior margin of clypeus, the absence of antennal scrobes, and the propodeal spiracles
located at almost midlength of the sclerite. Three species are recognized: L. gedensis sp. nov. from
Java, Indonesia, and L. gracilinoda sp. nov. and L. maryatiae sp. nov. both from Borneo, Malaysia.

Key words: Formicidae, Myrmicinae, Stenammini, new genus, new species, Indonesia, Malaysia.

Introduction

In the moist tropical forest zone of the Oriental
region the diversity of ants has yet been well under-
stood (Ogata, 1992; Yamane et al, 1996). In recent
years, collecting efforts by several myrmecologists
have produced a wealth of interesting and taxonomi-
cally important ants from Southeast Asia. In the
course of our study on the ant fauna of Southeast
Asia, we have examined several specimens of a new
genus, which belongs to the tribe Stenammini (sense
Bolton, 1994) of the subfamily Myrmicinae. Bolton
(1994) tentatively retained tribe Stenammini and in-
cluded 19 genera including an extinct genus. Al-
though classification at tribe rank within Myrmicinae
is nebulous and awaits detailed phylogenetic research-
es, and the tribe Stenammini also seems rather vague
and not sharply defined (Bolton, 1994; DuBois, 1998),
we describe the new distinctive geuns following
Bolton's view (1994).

The following abbreviations are used in this paper
for descriptions.

HL, head length: maximum full face view length
from the anteriormost margin of clypeus to the occip-
ital margin of the head (when the occipital margin is
concave, to a transverse line connecting its posterior-
most extensions).

HW, head width: maximum dorsal view distance
across head excluding eyes in full face view.

SL, scape length: length of scape excluding radicle.

CI, cephalic index: HW/HLX 100.

SI, scape index: SL/HWX 100.

WL, Weber's length of alitrunk: maximum diagonal
distance from the base of anterior slope of pronotum
to the propodeal lobe.

PW, pronotal width: maximum width of pronotum
in dorsal view.

PL, petiole length: maximum length of petiole in
lateral view, measured from ventral juncture with
propodeum to juncture with postpetiole.

PH, petiole height: maximum height of petiole in
lateral view, measured perpendicularly from apex of
petiolar node to venter of petiole.

DPW, petiole width: maximum width of petiole in
dorsal view.

PPL, postpetiole length: maximum length of post-
petiole in lateral view, measured from ventral juncture
with petiole to juncture with gaster.

PPH, postpetiole height: maximum height of post-
petiole in lateral view, measured perpendicularly from
apex of postpetiolar node to venter of postpetiole.
Vertical to the longitudinal axis of petiole.

PPW, postpetiole width: maximum width of petiole
in dorsal view.

TL, total body length: outstretched length from the
mandibular apex to the gastral apex.

Lasiomyrma gen. nov.

Type species: Lasiomyrma gedensis sp. nov.

Gender: feminine.

Diagnosis of worker. Monomorphic terrestrial myr-
micine ants with the following combination of charac-
ters.

1. Palp formula 2, 2 (one paratype specimen dis-

Mamoru TERAYAMA and Seiki YAMANE

sected).

2. Mandible elongate-triangular, with 7 teeth which
decrease in size from apex to base.

3. Anterior clypeal magin forming an obtuse angle,
lacking an isolated median seta.

4. Median portion of clypeus narrowly inserted be-
tween the frontal lobes.

5. Median portion of clypeus with a pair of weak
longitudinal carinae.

6. Frontal lobes narrow, each lobe almost as wide as
the median portion of clypeus that is inserted
between them.

7. Frontal carinae and antennal scrobes absent.

8. Eye moderate in size, positioned in front of the
midlength of the sides of the head.

9. Antenna 11-segmented; scape short (SI 60-70),
4th to 8th segments each wider than long; apical
3 segments forming a distinct club.

10. Alitrunk low in profile; promesonotal dorsum flat
or slightly convex, with dully angulate anterior
humeri, and widest at anterolateral angles.

1 1 . Metanotal groove present.

12. Propodeum with a pair of short teeth.

13. Propodeal spiracle located at or just behind of the
midlength of the sclerite, and high on side.

14. Propodeal lobe present, small to moderately long;
posteriormost portion forming an angle.

15. Metasternal process absent.

16. Tibial spurs absent on middle and hind legs.

17. Petiole pedunculate; subpetiolar process absent.

18. Cuticle thick and densely sculptured; pilosity fine
and dense over the dorsal surface of body.

Queen. Similar to the worker but larger in body
size. Ocelli present. Alitrunk with full complement of
flight sclerites and certainly winged when virgin.

Male. Unknown.

Remarks. Although the definition of the tribe
Stenammini is insufficient and phylogenetic analysis
among the genera within this tribe have not been
made, Lasiomyrma is positioned Stenammini follow-
ing Bolton's view (1994), which is a current under-
standing of the tribe based on the triangular mandible
with serrate teeth (character 2), the bicarinate clypeus
without median seta (characters 3 and 5), and the flat
or slightly convex promesonotal dorsum (character

.0).

Within the 18 genera of Stenammini excluding an
extinct genus, Lasiomyrma most resembles the genera
Indomyrma from India (Brown, 1985) and Tetheam-
yrma from Malaysia (Bolton, 1991) in sharing the 11-
segmented antennae (character 9) and the virtual
absence of antennal scrobes (character 7; weakly

defined in Indomyrma) (Bolton, pers. comm.). It is
distinguished from Indomyrma by the position of pro-
podeal spiracle (character 13; spiracle situated close to
the margin of propodeal declivity in Indomyrma) and
the absence of antennal scrobes (characeter 7), and
from Tetheamyrma by the 3-segmented antennal club
(character 9; 2-segmented in Tetheamyrma) and the
absence of spongiform appendages on ventral surfaces
of petiole and postpetiole. This new genus is separated
from the other stenammine genera by the combination
of the 11-segmented antennae with a 3-segmented
club, the obtusely angulate anterior margin of clypeus,
the absence of antennal scrobes, and the propodeal
spiracles located at almost modlength of the sclerite.
Character 3, the obtusely angulate anterior clypeal
margin, is possibly autapomorphic within this tribe.
Etymology: Lasio, Gr., hairy -hmyrma, Gr., ant.

Lasiomyrma gedensis sp. nov.

(Figs. 1-8)

Worker. HL 0.61 mm (holotype), 0.60-0.65 mm
(paratypes); HW 0.54 mm, 0.53-0.54 mm; SL 0.35
mm, 0.35-0.36 mm; CI 88, 86-89; SI 65, 65-67; WL
0.83 mm, 0.80-085 mm; PW 0.41 mm, 0.41-0.44 mm;
PL 0.28 mm, 0.28-0.29 mm; PH 0.24 mm, 0.24-0.25
mm; DPW 0.18mm, 0.1 7-0. 18 mm; PPL 0.16mm,
0.15-0.16 mm; PPH 0.20mm, 0.20-0.22 mm; PPW
0.20mm, 0.20-0.21 mm; TL 2.4mm, 2.3-2.4 mm.
(Holotype and 5 paratype workers were measured and
separately mentioned.)

Head 1.12-1.15 times as long as wide, with convex
sides and straight occipital margin in full face view;
surface densely punctate. Eye 0.13-0.14 mm in max-
imum diameter.

Alitrunk densely punctate, with slightly convex
promesonotal dorsum and convex propodeal dorsum;
anterior margin of promesonotum convex in dorsal
view; metanotal groove relatively deeply incised dor-
sally. Mesopleuron rather short, its maximum length
slightly longer than its length of ventral margin. Pro-
podeal spine longer than wide at base, with an acute
tip; propodeal declivity steep; propodeal lobe weakly
produced posteriorly.

Petiole longer than high; node thick; anterior face
much more steeply sloping than posterior face in
profile; anterior margin of node forming an obtuse
angle. Postpetiole higher than long in profile, highest
at posterior 1/3.

Gaster oval in dorsal view, largely smooth, scatterd
with small shallow punctures and 0.54 mm in maxi-
mum dorsal width.

Lasiomyrma, a New Stenammine Ant Genus

i

Rj^^BTSi

Figs. 1-8. Lasiomyrma gedensis sp. nov. 1-5, worker; 6-8, queen. 1, 6, Head in full face view; 2, body in profile; 3,

right mandible; 4, anterior margin of clypeus; 5, 8, alitrunk in dorsal view; 7, alitrunk, petiole and postpetiole in profile.
Scale bars: a, 0.5 mm for 1-3, 5-8; b, 0.5 mm for 4.

Body blackish brown; mandible and antenna yel-
lowish brown; legs brown.

Queen. HL 0.68 mm; HW 0.60 mm; SL 0.38 mm;
CI 89 mm; SI 63; WL 0.83 mm; PW 0.53 mm; PL 0.35
mm; PH 0.29mm; DPW 0.25mm; PPL 0.18mm;
PPH 0.18 mm; PPW 0.24 mm; TL 2.8 mm.

Head slightly longer than wide, with very weakly
convex sides and almost straight occipital margin in
full face view; surface densely punctate. Compound
eye 0.20 mm in maximum diameter. Ocelli forming an
obtuse triangle.

Alitrunk high, densely punctate, with slightly con-
vex dorsum. Pronotum wide, with convex anterior
margin and obtusely angulate humeri in dorsal view;
mesoscutum 0.80 times as long as wide, with convex
anterior margin in dorsal view; posterior margin of
metanotum broadly rounded in dorsal view; propodeal
spine short and obtusely angulate.

General shape of petiole and postpetiole largely as
in the worker.

Gaster oval in dorsal view; anterior 1/3 of 1st
tergite microreticulate; and the rest shallowly and
weakly punctate.

Holotype. Worker, Mt. Gede, West Java, Indone-

sia, Jan. 1991, F. Ito leg.

Paratypes. 9 workers, same data as in holotype; 1
queen, 4 workers, Gede-Pangrango National Park,
Java, Indonesia, 6. VI. 1997, K. Ohkawara leg.

Type depository. Holotype and some paratypes are
deposited in the Zoological Museum (Bogor) (Indo-
nesian Institute of Science, LIPI), and the other para-
types in the National Institute of Agro-Environmental
Sciences (Tsukuba), Museum of Nature and Human
Activities (Hyogo), Faculty of Science, Kagoshima
University (Kagoshima), and the Natural History
Museum (London).

Etymology. The specific epithet referes to the type
locality.

Remarks. The type series includes specimens from
two colonies, which were taken from rotten wood on
the forest floor. This species is distinguished from the
other congeners by the convex propodeal dorsum in
profile, the obtuse angle of the anterior slope of petio-
lar node, and the straight occipital margin of head in
full face view.

Mamoru TERAYAMA and Seiki YAMANE

Lasiomyrma gracilinoda sp. nov.

(Figs. 9-10)

Worker. HL 0.56 mm; HW 0.48 mm; SL 0.31 mm;
CI 84; SI 66; WL 0.68mm; PW 0.40mm; PL 0.21
mm; PH 0.23mm; DPW 0.16mm; PPL 0.15mm;
PPH 0.18 mm; PPW 0.20 mm; TL 2.1 mm.

Head 1.17 times as long as wide, coarsely punctate,
with very weakly concave occipital margin in full face
view; sides behind eyes subparallel. Eye 0. 1 8 mm in
maximum diameter.

Alitrunk densely punctate, with largely straight pro-
mesonotal dorsum excepting the posterior portion
weakly convex, and straight propodeal dorsum; meta-
notal groove shallow. Mesopleuron rather short, its
maximum length slightly longer than its length of
ventral margin. Propodeal spine thin, longer than
wide at base; propodeal declivity steep; propodeal lobe
weakly produced posteriorly.

Petiole slightly higher than long, with a thin node in
profile; node reversed V-shaped with a bluntly pro-
duced dorsum. Postpetiole slightly longer than high,
with convex dorsal margin in profile.

Gaster with shallow small punctures that are mod-
erately spaced, in dorsal view 0.49 mm in maximum
width.

Body reddish brown; mandible and antenna yellow;
legs brown.

Holotype. Worker, Poring (600 m alt.), Kinabalu
Park, Sabah, Borneo, Malaysia, 29. X. 1996, T. Kiku-
ta leg.

Type depository. Tropical Biology and Conserva-
tion Unit, Malaysia Sabah University, Kota Kinabalu.

Etymology. Named after its thin petiolar node in
profile.

Remarks. This species is distinguished from L.
gedensis sp. nov. by the straight propedeal dorsum, the
absence of an angle of anterior slope of petiolar node
and the concave occipital margin of head in full face
view, and from L. maryatiae sp. nov. by the thinner
petiolar node, the shorter mesopleuron and the weakly
produced propodeal lobe. Known only from the holo-
type.

Lasiomyrma maryatiae sp. nov.

(Figs. 11-12)

Worker. HL 0.55 mm; HW 0.45 mm; SL 0.30 mm;
CI 82; SI 67; WL 0.65 mm; PW 0.39 mm; PL 0.23
mm; PH 0.23mm; DPW 0.14mm; PPL 0.15mm;
PPH 0.16 mm; PPW 0.18 mm; TL 2.2 mm.

Head 1.22 times as long as wide, densely punctate,
with evenly convex sides and weakly concave occipital
margin in full face view. Eye 0.14mm in maximum
diameter.

Alitrunk densely punctate, with flat promesonotal
and propodeal dorsa; metanotal groove shallow; pro-
podeal spine as long as wide at base; propodeal decliv-
ity gently sloping to propodeal lobe; propodeal lobe
produced posteriorly. Mesopleuron long, its maxi-
mum length distinctly longer than its length of ventral
margin.

I

Figs. 9-12. Workers of Lasiomyrma gracilinoda sp. nov. (9, 10) and L. maryatiae sp. nov. (11, 12)
face view; 10, 12, body in profile. Scale bar: 0.5 mm.

9, 11, Head in full

Lasiomyrma, a New Stenammine Ant Genus

Petiole as long as high; node thick, reversed U-
shaped in profile. Postpetiole higher than long, with
convex dorsal margin in profile.

Gaster with shallow and small punctures that are
moderately spaced, in dorsal view 0.49 mm in maxi-
mum width.

Body blackish brown; mandible and antenna yel-
low; legs brown.

Holotype. Worker, Poring (550m), Sabah, Bor-
neo, E. Malaysia, 17. III. 1995, Sk. Yamane leg.

Type depository. Tropical Biology and Conserva-
tion Unit, Malaysia Sabah University, Kota Kinabalu.

Etymology. The specific epithet is dedicated to Dr.
Maryati Mohamed of Universiti Malaysia Sabah.

Remarks. This species is distinguished from L.
gedensis sp. nov. by the straight propedeal dorsum, the
absence of an angle of anterior slope of petiolar node
and the concave occipital margin of head in full face
view, and from L. gracilinoda sp. nov. by the thicker
petiolar node, the longer mesopleuron and the strong-
ly produced propodeal lobe. Known only from the
holotype.

Key to the species of the genus Lasiomyrma

1. Propodeal dorsum convex in profile; anterior de-
clivity of petiolar node steep, and in profile poste-
rior margin of petiolar peduncle connected to the
anterior slope of node at an obtuse angle
L. gedensis sp. nov.

- Propodeal dorsum straight in profile; anterior
face of petiolar node sloping down to peduncle,
without forming an angle 2

2. Petiolar node thin (Fig. 10), narrowed above in
profile; propodeal lobe weakly produced pos-
teriorly L. gracilinoda sp. nov.

- Petiolar node thick (Fig. 12), reversed U-shaped
in profile; propodeal lobe strongly produced pos-
teriorly L. maryatiae sp. nov.

Acknowledgments

We thank Drs. F. Ito (Kagawa Univ.), K. Ohka-
wara (Kanazawa Univ.), and Mr. T. Kikuta (Hokka-
ido Univ.) for their offer of valuable material, and Mr.
B. Bolton (The Natural History Museum, London)
for his useful comments on the material. We also
thank Dr. M. Mohamed (Univ. Malaysia Sabah) for
her kind help and encouragement.

References

Bolton, B. 1991. New myrmicine ant genera from the Oriental
region (Hymenoptera: Formicidae). Systematic Entomolo-
gy, 16: 1-13.

Bolton, B. 1994. Identification guide to the ant genera of the
world. Harvard University Press, Cambridge, Massachu-
setts.

Brown, W. L., Jr. 1986 (1985). Indomyrma dasypyx, new genus
and species, a myrmicine ant from Peninsular India. Israel
Journal of Entomology, 19: 37-49.

DuBois, M. B. 1998. A revision of the ant genus Stenamma in
the Palaearctic and Oriental regions. Sociobiology, 32: 193-
403.

Ogata, K. 1992. The ant fauna of the Oriental Region: an
overview (Hymenoptera, Formicidae). Bulletin of the
Institute of Tropical Agriculture, Kyushu University, 15: 55-
74.

Yamane, Sk., Itino, T. & Nona, A. R. 1996. Ground ant fauna
in a Bornean dipterocarp forest. The Raffles Bulletin of
Zoology, 44: 253-262.

(Received April 7, 1999; Accepted May 9, 2000)